Blasted Donjon of the Erdukr Dwarves (5E)

From publisher blurb:

For decades, the Erdukr dwarves have been a dwindling folk. But now, all contact with their ancient hold has ceased. What doom has befallen the dwarves? Did they dig too deep, did their ancient enemies, the Orcs of the Flayed Skull, finally triumph, or did some other doom befall them? Whatever the cause of their fall, the answer lies in the Blasted Donjon of the Erdukr Dwarves!